Global Warming Linked to Kidney Stones

Could global warming lead to more kidney stones? A new study has found that high daily temperatures mirror the number of patients seeking treatment for kidney stones.

The findings, published in the journal Environmental Health Perspectives, are based on analysis of hot days and kidney stones in 60,000 patients in several U.S. cities with varying climates.

"We found that as daily temperatures rise, there is a rapid increase in the probability of patients presenting over the next 20 days with kidney stones," said lead researcher Gregory E. Tasian, M.D., a pediatric urologist at The Children's Hospital of Philadelphia and staff member with the facility's Kidney Stone Center.

The researchers noted higher temperatures contribute to dehydration, which can lead to a higher concentration of calcium and other minerals in the urine that promote the growth of kidney stones.

The study, which was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, examined medical records of kidney stone sufferers between 2005 and 2011 in Atlanta, Chicago, Dallas, Los Angeles, and Philadelphia. The researchers compared the medical charts with weather data.

The results showed that as mean daily temperatures rose above 50 Fahrenheit, the risk of kidney stones increased in all the cities except Los Angeles — peaking within three days of exposure to hot days.

They also showed very low outdoor temperatures increased the risk of kidney stones in three cities: Atlanta, Chicago, and Philadelphia. The researchers suggested that as cold weather keeps people indoors more, higher indoor temperatures, changes in diet and decreased physical activity may raise their risk of kidney stones.

"These findings point to potential public health effects associated with global climate change," said Dr. Tasian. "However, although 11 percent of the U.S. population has had kidney stones, most people have not. It is likely that higher temperatures increase the risk of kidney stones in those people predisposed to stone formation."

Kidney stones have increased markedly in the past three decades. When painful stones do not pass on their own, surgery is often necessary.